Embodiments relate to a display device, and more particularly, to a display device, which more precisely detects luminance of a lighting source.
Liquid crystal displays (LCDs) display images using electrical and optical properties of liquid crystal. The LCDs have lots of advantageous merits such as thinness, lightness, low power consumption, and low operational voltage so that the LCDs are widely used for a variety of industrial fields.
Such an LCD includes a liquid crystal display panel in which liquid crystal is injected and encapsulated between two sheets of transparent substrates and a voltage is applied to change the orientation of liquid crystal molecules and vary optical transmittance, thereby optically displaying images and a backlight assembly for providing light to the liquid crystal display panel.
A cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a flat fluorescent lamp (FFL), and the like are used as light sources of the backlight assembly.
However, since the CCGL has disadvantages in that it is difficult to realize high-fidelity devices and light, thin, and small devices, light emitting diodes (LEDs) having improved performance such as high luminance, long lifetime, and high color purity are being widely used as lighting sources. Furthermore, since the regulation of a toxic environmental substance such as mercury has been greatly reinforced, the use of the CCFL is being gradually decreased. Thus, the changeover to the LEDs that are the environment-friendly products is a trend.
An LCD using the backlight assembly as a lighting source should have uniform illumination and intensity of the lighting source. However, the lighting source has a significant influence on its surroundings and operation time.
FIG. 1 is a graph of an illumination variation according to an operation time of a general lighting source.
Referring to FIG. 1, the lighting source is changed in illumination in proportion to an operation time.
That is, the lighting source has a limitation that the illumination and intensity thereof are non-uniformly changed by its surroundings and operation time.
Here, when the illumination and intensity of the lighting source are non-uniform, an image displayed on a display device is deteriorated in the image quality. Specifically, when illumination and intensity of a lighting source used for a medical display device are deteriorated, there is a limitation that it is difficult to check precise conditions of patients.
Thus, it is necessary to seek for acceptable solution to uniformly maintain the illumination and intensity of the lighting source in the display device using the backlight assembly as the lighting source.